1D-Systems

Phonons in 1D-structures

Electron-phonon coupling is at the core of many fundamental processes in material science, from superconductivity to material degradation. The combined description of electron-ion dynamics is of fundamental relevance to address the decaying mechanism and how those are affected by the 1D nature of the structures. Besides leading to temperature dependent broadening of optical spectral features this coupling can be use to control and monitor chemical reactions (and assembling) at surfaces

Magnetic effects in nanostructures

Low-dimensionality causes non-magnetic bulk material to exhibit magnetic response: this has important consequences for applications and up to now is poorly understood. The proper treatment requires the introduction of spin-orbit effects (magnetic anisotropy) and the existence of non-collinear magnetic structures. This task requires fundamental advances in the many-body (self-energy) description of electron correlations and, consequently, in the development of proper exchange-correlation functionals within TD-DFT. One natural application would be to study spintronics (spin-transport through molecular structures) and the behaviour of magnetic nanostructures supported on surfaces.

Nanowires, nanotubes, conjugated polymers including their composites and the environment (packing effects)

We have two main tasks:

• One, calculate the optical spectra of free-standing and interacting silicon wires as well as the effective electron-electron interaction influence of surface passivation on their structural properties. We will also study the electronic structure of metallic nanowires on semiconductor surfaces, as explained in C3, and the optical and EELS spectra of isolated carbon and boronnitride nanotubes. As a way towards complexity, we will tackle the analysis of response properties of more complicated structures, like multiwall nanotubes, the inclusion of other materials, and their 3D assemblies.
• Second, study the packing effects in the efficiency of polymer-based LEDs. We will also shed light on the nanotube/polymer precursor interaction, which is responsible of a change of the effective polymer conversion temperature thus influencing the efficiency of polymer-based LEDs. Finally, we will study the cohesion and resistance to light degradation of tube/polymer composites.

1D-Organic molecules on surfaces

We will study of the role played by defects, and of water, oxygen and organic groups attached to the 1D-structures in the electronic properties. We will also address the optimal control of laser pulses to achieve a desired binding or desorption of molecules. This works goes towards the development of chemical and biological sensors (e.g, nanotubes have been shown to exhibit important changes of conductivity upon absorption of different gases and enzymes, this, of course, needs to be quantified and controlled).